Current ruminant feeds and feeding practices rely heavily on readily fermentable carbohydrates and chopped, ensiled forages. Such feeds generate acids in the rumen which are not completely counterbalanced by dietary or endogenous bases and buffers. Under more acidic conditions, the population of microorganisms found in the rumen is less desirable than the population found under less acidic or neutral conditions. Under these less acidic or neutral conditions, rumen microorganisms produce more fatty acids which can be used by the lactating animal to produce milk fat.
It is known that sodium bicarbonate and magnesium oxide, alone or in combination, are effective in increasing the milk and/or milk fat production of animals fed on high acid-producing diets. Chalupa and Kronfeld, 1983, Animal Nutrition and Health, May--June, 50; Erdman, et al. 1982, Journal of Dairy Science, 65, 712; Erdman, et al. 1980, Journal of Dairy Science, 63, 923; and Kilmer et al. 1980, Journal of Dairy Science, 63, 2026. However, these additives have the undesirable effects of temporarily reducing the feed intake and decreasing the serum levels of potassium and magnesium. Improved methods for increasing milk fat production using new compositions and methods are therefore continually needed.